CN102305666A

CN102305666A - Method and equipment for measuring day-time seeing based on solar apparent diameter variance measurement

Info

Publication number: CN102305666A
Application number: CN 201110242172
Authority: CN
Inventors: 金振宇; 刘忠
Original assignee: Yunnan Astronomical Observatory of CAS
Current assignee: Yunnan Astronomical Observatory of CAS
Priority date: 2011-08-23
Filing date: 2011-08-23
Publication date: 2012-01-04
Anticipated expiration: 2031-08-23
Also published as: CN102305666B

Abstract

The present invention is a kind of daytime seeing measurement method based on the measurement of solar apparent diameter variance. With the telescope that a bore is between 50mm to 100mm, with the large area array detector that can shoot full-time image surface in the image planes of telescope, short exposure time is shot; lt; The full-time image surface of 10ms measures the apparent diameter of the sun from the full-time image surface of each frame, calculates apparent diameter variance from a series of solar apparent diameters of measurement, and apparent diameter variance is substituted into formula: , daytime Seeing parameter r0 value is calculated. Influence of the present invention due to effectively avoiding near surface turbulence atmosphere, when measurement, does not need plateau i.e. and can measure the atmospheric seeing of 20m or more, and contains the influence of near surface turbulence atmosphere in the measurement result of classics S-DIMM. Device structure of the invention is light and handy, light-weight, easy to carry, is very suitable for the preliminary reconnaissance phase of Astronomical Site Testing.

Description

Daytime seeing measuring method and equipment based on the measurement of solar apparent diameter variance

Technical field

The present invention relates to the astronomical surveing technical field, specifically is a kind of daytime seeing measuring method and equipment of measuring based on the solar apparent diameter variance.

Background technology

The seeing parameter of earth atmosphere (is used r usually ₀Represent) the relevant diameter of atmosphere when light wave passes through the atmospheric turbulence media imaging has been described, it has determined the resolution of ground in the face of extraterrestrial target observation, is the major parameter that must survey in the astronomical addressing.The measurement of seeing parameter must be indispensable in fields such as astronomical high-resolution imaging, adaptive optics.

Currently, the Earth's atmosphere at home and abroad for seeing the main parameters of the differential measurement techniques like sports law and scintillation method, in which the differential movement like Sarazin and Roddier method is proposed by the atmospheric seeing measurement method, the principle is: the use of double- Hitomi telescope while observing the same point source single star in the image plane of the telescope to get separated two star image, since the two stars like the wave front through the different atmospheric optical path between the two stars as the relative position with wave the ups and downs before the change, so by measuring and calculating two stars like the relative motion between the variance obtained by the following two equations of atmospheric seeing parameter r ₀.

(1)

Figure 2011102421726100002DEST_PATH_IMAGE002

(2)

Where

and are vertical (Double Vision Center connection direction) variance and transverse (perpendicular to the direction of the connection with the Double Vision Center) variance,

is the center wavelength of light, D is the Double Vision binoculars two sub-hole diameter, d is the two sub-hole centers distance.This measuring method is called " the Differential Image method of movement ", and surveying instrument is called " Differential Image motion monitoring appearance ", and english abbreviation is DIMM.

This method and apparatus is used for the measurement of night-time seeing, but can not be applied to the measurement of daytime seeing, but this is because the daytime has only observation body of the sun, and is a big face source.Through improvement, develop " sun Differential Image motion daytime seeing measuring instrument " to DIMM for this reason.The concrete scheme of this measuring method is: utilize a certain section solar limb of double vision telescope observation; Utilize a bit of solar limb picture of slit intercepting at the mirror image face of looking in the distance; Thereafter obtaining two the separated homology double images forming behind the different atmosphere light paths of passing through of this solar limb with an optical wavefront segmenting system, the variance through the relative motion between the picture of two edges obtains daytime seeing parameter r through (1) formula ₀This method and apparatus abbreviates S-DIMM as, and Fig. 1 is the synoptic diagram of S-DIMM.It is between 3 times to 4 times of sub-bore dia that S-DIMM requires two sub-pitchs of holes; Only relevant for the relative motion that guarantees two solar limb pictures simultaneously with turbulent atmosphere; Normally the mask that two sub-aperture are installed on the 300mm telescope is realized, in the monitoring of therefore be generally used for fixing a point, long-term seeing being measured.

Need carry out preliminary seeing to a lot of areas in the preliminary reconnaissance phase of astronomical addressing measures; A lot of regional conditions are arduouser; The equipment that need carry is walked very long road on foot, because the bigger and Heavy Weight of S-DIMM, the seeing that therefore is not suitable for the preliminary reconnaissance phase is measured.In actual astronomical sight, astronomical telescope is on buildings in addition, and 15 meters turbulent atmospheres below-20 meters near the ground are can not influence astronomical sight, therefore the influence that need not measure 15 meters turbulent atmospheres below-20 meters near the ground.By day, because ground receives the irradiation of the sun, surface temperature is apparently higher than temperature, and the refractive index fluctuation that therefore common turbulent atmosphere below 20 meters near the ground causes can compare seriously.And if S-DIMM is placed on ground, then inevitably receive the influence of atmospheric turbulence near the ground, thereby local seeing situation is correctly estimated in influence.In order to eliminate the influence of near surface turbulence atmosphere, must build the building more than 10 meters, S-DIMM is installed on the buildings, but the primary election stage in order to save time and cost, can not build buildings.Therefore need light, effectively to eliminate the equipment that atmospheric turbulence near the ground influences and can carry out the seeing parameter measures of quantization in the preliminary reconnaissance phase of astronomical addressing.

Background technology

Key in technical field herein and describe paragraph.

Summary of the invention

The objective of the invention is to propose a kind of based on variation variance measurement daytime seeing parameter r through solar apparent diameter ₀Method and apparatus (portable daytime seeing measuring instrument P-SDIMM).It can effectively be eliminated under the prerequisite of influence of near surface turbulence atmosphere daytime seeing parameter is carried out measures of quantization,

The inventor finds that the variation of solar apparent diameter is that the influence that only receives turbulent atmosphere produces, so the variation variance of solar apparent diameter has reflected the seeing of turbulent atmosphere.Simultaneously owing near the ground very high correlativity arranged, insensitive to the refractive index fluctuation of near surface turbulence atmosphere, therefore can eliminate the influence of near surface turbulence atmosphere effectively.On this basis, the inventor according to the analytical derivation of the correlativity of the refractive index fluctuation of the turbulent atmosphere of Fired calculate the formula of seeing parameter, its formula is following:

Figure 2011102421726100002DEST_PATH_IMAGE006

?(3)

Where

is the variance of the apparent diameter of the sun,

is the center wavelength of light, D is the diameter of the telescope.

Based on this inventive concept following technical scheme of the present invention has been proposed:

Use a bore as 50mm to the telescope between the 100mm, with taking the big planar array detector of full-time picture, take the short exposure (time shutter on the telescopical image planes<10ms) full-time picture utilizes edge detecting technology to measure the visual diameter of the sun from full-time picture of each frame, calculates the visual diameter variance from a series of solar apparent diameters of measuring, and visual diameter variance substitution formula (3) is calculated daytime seeing parameter r ₀Value.

Used telescope adopts 90mm Maksutov-Cassegrain telescope, and telescope is by corrector, and three assemblies of secondary mirror and primary mirror constitute imaging system.Add the dim light optical filter at the entrance pupil place, be used to weaken sunshine; Added detector at the telescope focal plane, detector area is greater than the sun picture on the focal plane, can be big area array CCD, also can be big face battle array digital camera.

The running parameter of this application example is: bore 90mm, the burnt long 1250mm of equivalence, time shutter 1ms, sample frequency>3Hz, statistical sample is several 60, about reduction of carrying out a visual diameter variance in 20 seconds.Telescope can carry out seeing monitoring continuously for a long time if automatic tracking system is arranged.

The invention has the beneficial effects as follows: portable daytime seeing measuring instrument P-SDIMM compares with classical S-DIMM has following two advantages:

1. owing to effectively avoided the influence of near surface turbulence atmosphere, do not need high platform can measure the above atmospheric seeing of 20m during measurement, and comprised the influence of near surface turbulence atmosphere in the measurement result of classical S-DIMM.

2. structure is light and handy, in light weight, is easy to carry, and is very suitable for the preliminary reconnaissance phase of astronomical addressing.

Summary of the invention

Key in technical field herein and describe paragraph.

Description of drawings

Fig. 1 is the structural representation of SDIMM.

Among Fig. 1,1. incident sunshine, 2. entrance pupil optical filter; 3. double vision mask, 4. telescope imaging mirror, 5. optical filter; 6. the slit on the image planes for the first time, the 7. solar limb slit on the image planes for the first time, 8. the solar limb echo of slit intercepting on the image planes for the first time; 9. collimating mirror; 10. Differential Image mask, 11. wedges, 12. secondary imaging mirrors; 13. the separated homology solar limb echo that opens on the imaging surface for the second time, 14. CCD.

Fig. 2 is the structural representation of P-SDIMM of the present invention.

1. incident sunshine, 2. dim light optical filter, 3. corrector, 4. secondary mirror, 5. primary mirror, 6. CCD.

Embodiment

Be illustrated in figure 2 as the instance of P-SDIMM, telescope adopts 90mm Maksutov-Cassegrain telescope, and telescope is by

corrector

3, and 5 three assemblies of secondary mirror 4 and primary mirror constitute imaging system.Add dim light optical filter 2 at the entrance pupil place, be used to weaken sunshine.Added detector 6 at the telescope focal plane, detector area is greater than the sun picture on the focal plane, can be big area array CCD, also can be big face battle array digital camera, consider from the angle of cost in this instance, employing be single anti-digital camera.The running parameter of this application example is: bore 90mm, the burnt long 1250mm of equivalence, time shutter 1ms, sample frequency>3Hz, statistical sample is several 60, about reduction of carrying out a visual diameter variance in 20 seconds.Telescope can carry out seeing monitoring continuously for a long time if automatic tracking system is arranged.

Take full-time picture of short exposure (time shutter < 10ms) with this telescope, from full-time picture of each frame, utilize edge detecting technology to measure the visual diameter of the sun, calculate the visual diameter variances from a series of solar apparent diameters of measuring, visual diameter variance substitution formula

Calculate daytime seeing parameter r ₀Value.

Claims

1. daytime seeing measuring method of measuring based on the solar apparent diameter variance; It is characterized in that using a bore as 50mm to the telescope between the 100mm; Use the big planar array detector that to take full-time picture on the telescopical image planes; Take short exposure time < full-time the picture of 10ms; From full-time picture of each frame, measure the visual diameter of the sun; Calculate the visual diameter variance from a series of solar apparent diameters of measuring, with visual diameter variance substitution formula (3)

（3）

Calculate daytime seeing parameter r ₀Value.

2. the described daytime seeing measuring equipment of measuring based on the solar apparent diameter variance of a claim 1; It is characterized in that adopting 90mm Maksutov-Cassegrain telescope; Telescope is by corrector; Three assemblies of secondary mirror and primary mirror constitute imaging system; Added the dim light optical filter at the entrance pupil place, added detector at the telescope focal plane.

3. the daytime seeing measuring equipment of measuring based on the solar apparent diameter variance according to claim 2 is characterized in that described detector area is greater than the sun picture on the focal plane, adopts big area array CCD, or big face battle array digital camera.